This invention relates generally to air conditioning systems and, more particularly, to piping and valving arrangements for the continuous metered flow of refrigerant in a multizone air conditioning system.
In a multizone air conditioning or heat pump system, where multiple indoor coils are used in combination with a single outdoor coil, it is common practice to provide valves at each end of the individual fan coil circuits so that, at any one time, any of the fan coil circuits may be effectively removed from the active system by simply closing its associated valves. It is thus common in such systems that, at any one time, one or more fan coil circuits are in such an inactive status while one or more other fan coil circuits are operating as part of the active system. It is also common to periodically interchange the active and inactive fan coil circuits by the opening and closing of their associated valves.
Heretofore, the manufacturers of multizone air conditioning or heat pump systems have strived to obtain high quality valves with little or no leakage so as to thereby completely shut off refrigerant flow to a particular fan coil when its thermostat was satisfied. The reason for this was that a leaking solenoid would cause refrigerant and its entrained oil to be trapped in the isolated circuit to thereby remove the oil from the active circuit where it was needed for the proper lubrication of the compressor. Although this problem may be somewhat alleviated by the use of high quality valves that have very little leakage, there is an associated problem which is exacerbated by this practice. That is the problem of noise which is caused to occur when such a valve is opened and the refrigerant rushes from the high side to the low side of the valve.
When a fan coil circuit is in an inactive state with its associated valves closed, there is little, if any, refrigerant in the circuit and that circuit is therefore under a low pressure condition. On the other side of the control valve which separates that circuit from the high pressure side of the active system, however, there is a high pressure condition. Thus, when that valve is opened to bring the inactive coil circuit into an active status, the sudden pressure drop across the valve causes a rapid flow of refrigerant and a substantial resultant noise which tends to be conducted along the insulated refrigerant line(s) to the fan coil(s) within the building. These temporary, but reoccurring, noises tend to be amplified by the fan coil(s) and can be annoying to anyone in the immediate area.
It is therefore an object of the present invention to provide a multizone air conditioning system with reduced operational noise.
Another object of the present invention is the provision in a multizone air conditioning system for reducing the occurrence of trapped oil in an inactive coil circuit while, at the same time, minimizing the noise caused by the opening of valves.
Still another object of the present invention is the provision in a multizone air conditioning system for accommodating the periodic opening of fan coil valves without any appreciable noise effects.
Yet another object of the present invention is the provision in a multi-fan coil air conditioning apparatus for quietly and efficiently bringing fan coil circuits into and out of the active mode during periodic intervals.
Still another object of the present invention is the provision for a multizone air conditioning system which is economical to manufacture and extremely functional in use.
These objects and other features and advantages become more readily apparent upon reference to the following description when taken in conjunction with the appended drawings.